Delphi中Chrome Chromium、Cef3學習筆記（三）

原文   http://blog.csdn.net/xtfnpgy/article/details/46635871

Delphi與JS的互動問題：

一、執行簡單的JS

上一篇已經講過:

chrm1.browser.MainFrame.ExecuteJavaScript('alert("abc");','about:blank',0);

chrm1.browser.MainFrame.ExecuteJavaScript('function aaa(){alert("abc");}aaa();','about:blank',0);

二、注入自定義的JS

首先必須在網頁加載完成之後，才可以執行，不能為空頁面！

str_js := 'var oScript = document.createElement( "script" );oScript.id = "sid";alert(oScript.id);';

chrm1.browser.MainFrame.ExecuteJavaScript(str_js,'about:blank',0);

三、delphi與JS互動（通過ceflib實作）

Cef3的Demo裡面，有一個cefclient的例子，可以看下，關鍵代碼：

TExtension = class(TCefv8HandlerOwn)
  private
    FTestParam: ustring;
  protected
    function Execute(const name: ustring; const obj: ICefv8Value;
      const arguments: TCefv8ValueArray; var retval: ICefv8Value;
      var exception: ustring): Boolean; override;  //重寫Execute事件
  end;      

//通過不同的name，執行不同的動作

function TExtension.Execute(const name: ustring; const obj: ICefv8Value;
  const arguments: TCefv8ValueArray; var retval: ICefv8Value;
  var exception: ustring): Boolean;
begin
  if(name = 'SetTestParam') then
  begin
    // Handle the SetTestParam native function by saving the string argument
    // into the local member.
    if (Length(arguments) <> 1) or (not arguments[0].IsString) then
    begin
      Result := false;
      Exit;
    end;
    FTestParam := arguments[0].GetStringValue;  //多個參數arguments[i].GetStringValue 依次類推
    Result := true;
  end
  else if(name = 'GetTestParam') then
  begin
    // Handle the GetTestParam native function by returning the local member
    // value.
    retval := TCefv8ValueRef.CreateString(Ftestparam);
    Result := true;
  end
  else if (name = 'GetTestObject') then
  begin
    // Handle the GetTestObject native function by creating and returning a
    // new V8 object.
    retval := TCefv8ValueRef.CreateObject(nil);
    // Add a string parameter to the new V8 object.
    retval.SetValueByKey('param', TCefv8ValueRef.CreateString(
        'Retrieving a parameter on a native object succeeded.'));
    // Add a function to the new V8 object.
    retval.SetValueByKey('GetMessage',
        TCefv8ValueRef.CreateFunction('GetMessage', Self));
    Result := true;
  end
  else if(name = 'GetMessage') then
  begin
    // Handle the GetMessage object function by returning a string.
    retval := TCefv8ValueRef.CreateString(
        'Calling a function on a native object succeeded.');
    Result := true;
  end else
    Result := false;
end;      

{ 注冊JS擴充 }

procedure RegisterExtension;
var
  Code: string;
begin
  Code :=
    'var cef;if(!cef)cef={};if(!cef.taobao)cef.taobao={};(function(){cef.taobao.test_object=function(){native function GetTestObject();return GetTestObject();};})();';
  if Code <> '' then
  try
    CefRegisterExtension('example/v8',Code,TExtension.Create as ICefv8Handler);
  except
  end;
end;      

在FormCreate中注冊類：

RegisterExtension;

調用執行個體：

chrm1.browser.MainFrame.ExecuteJavaScript('alert("abc");','about:blank',0);

  str_temp := 'function aaa(){var CefObj = new cef.taobao.test_object;'+  //先new一個執行個體對象

               'CefObj.SetTestParam("abc");var b=CefObj.GetTestParam();alert(b);'+   //設定、擷取、輸出參數

               '}aaa();';

  chrm1.Browser.MainFrame.ExecuteJavaScript(str_temp,'about:blank',0);

如果要實作多個參數，可以定義個數組替代FTestParam 

  private

    FTestParam : ustring;

    ArrayParam : array of ustring;  //多個參數

關鍵代碼：

if(name = 'SetTestParam') then
  begin
// **************原來一個參數的情況**********
//    if (Length(arguments) <> 1) or (not arguments[0].IsString) then
//    begin
//      Result := false;
//      Exit;
//    end;
//    FTestParam  := arguments[0].GetStringValue;
// **************原來一個參數的情況**********
    SetLength(ArrayParam,Length(arguments));
    for  i := 0 to Length(arguments) - 1 do
    begin
      ArrayParam[i] := arguments[i].GetStringValue;
      if s='' then
        s := ArrayParam[i]
      else
        s  := s+','+ArrayParam[i];
    end;
    FTestParam  := s;
  end
  else if(name = 'GetTestParam') then
  begin
// **************原來一個參數的情況**********
//    retval := TCefv8ValueRef.CreateString(FTestParam);
// **************原來一個參數的情況**********
    for  i := 0 to Length(ArrayParam) - 1 do
    begin
      if s='' then
        s := ArrayParam[i]
      else
        s  := s+','+ArrayParam[i];
    end;
    retval := TCefv8ValueRef.CreateString(FTestParam);
  end;      

這樣調用GetTestParam傳回的還是一個字元串，多個參數用逗号隔開了而已，可以對其再進行改寫即可；